An Optical Network Terminal (ONT) is a device used in fiber optic communication networks. It is typically installed at the customer's premises and acts as a bridge between the service provider's fiber optic network and the customer's local area network (LAN) or individual devices.

The ONT serves as the interface between the optical fiber cable coming from the service provider's network and the customer's devices, such as computers, phones, or routers. It converts the optical signals transmitted over the fiber optic cable into electrical signals that can be understood by the customer's equipment. Similarly, it also converts the electrical signals from the customer's devices into optical signals for transmission back to the service provider.

The Optical Network Terminal (ONT) performs various functions, including signal modulation, demodulation, multiplexing, and demultiplexing. It may also include additional features such as Ethernet ports, voice ports for telephone services, and video ports for television services. Depending on the service provider and the specific network setup, an ONT may be a standalone device or integrated into a larger network termination unit (NTU) or a modem.

In summary, an Optical Network Terminal (ONT) is a crucial component in fiber optic communication networks, allowing the seamless transmission of data, voice, and video services between service providers and customers.